Grimsby, Canada offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Grimsby, Ontario, Canada, is known for the Beamer Memorial Conservation Area and its annual raptor migration. The best time to travel to Grimsby, Canada, is during the summer months of June to August, when the average air temperature is around 20-25°C (68-77°F) and the water temperature in nearby Lake Ontario is approximately 18-22°C (64-72°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!